Generally, in this kind of label printer, a long ground paper on which a label is attached is fed by a platen, and data is printed on the label by a thermal head opposed to the platen. A peeling plate is located on a downstream side of the platen, and a ground paper feeder is located on a downstream side of the peeling plate, so that the ground paper may be stretched by the ground paper feeder, and thereby a data printed label may be peeled off by the peeling plate, thus issuing the data printed label.
The ground paper feeder includes a drive roller formed of rubber and a pinch roller formed of metal for pressing the ground paper onto the drive roller. The ground paper feeding speed at the ground paper feeder is set lower than the ground paper feeding speed at the platen, so as to reliably peel off the label from the ground paper at the peeling plate. Further, the ground paper stretching force at the ground paper feeder is set smaller than the ground paper holding force by the platen and the thermal head, so as to prevent slip of the ground paper between the platen and the thermal head and to secure a printing operation on the labels.
However, the above-mentioned prior art has the following shortcomings. As the ground paper feeding speed at the ground paper feeder is higher than the ground paper feeding speed at the platen portion, and the ground paper stretching force is smaller, there is generated slip between the drive roller and the ground paper. This causes wear at the portion of the drive roller that is in contact with the pinch roller through the ground paper since the drive roller is formed of rubber, which is less wear resistant. When the drive roller is worn, the outer circumference of the drive roller is reduced by the amount of wearing. As a result, the peripheral speed of the drive roller is decreased, and the ground paper holding force generated by the drive roller and the pinch roller is weakened. This in turn causes a problem such that the necessary speed and stretching force for peeling off the label cannot be obtained at the ground paper feeder and the label cannot be peeled off.
Further, the coefficient of friction between rubber and paper is about 0.4, and accordingly, such an increased coefficient of friction causes easy generation of a wearing powder of the rubber and the paper because of the slip therebetween. If the wearing powder is stacked in the device, there is increased a possibility of the wearing powder depositing on the ink ribbon or on the labels, thereby causing reduction in the printing quality.